1. Field of the Invention
The present invention relates to an ink cartridge used for an ink jet printer and a loading mechanism for such an ink cartridge.
2. Description of the Prior Art
Printers designed to make a recording using a liquid ink, particularly ink jet printers, use an ink cartridge such as disclosed by the present applicant in Japanese Patent Publications Nos. Hei. 5-270001 and Hei. 7-125238.
An ink cartridge of this type is usually formed of polystyrene having an appropriate degree of shape keeping property, and an ink is charged into such ink cartridge under reduced pressure. Since polystyrene is easily permeated by water vapor, if the ink cartridge has been in storage for a long period of time, the viscosity of the ink is increased due to evaporation of moisture, which in turn imposes the problem of defective jetting of ink droplets out of nozzles and hence impairs reliability. In addition, if an ink whose surface tension is low is used to allow ink droplets to be jetted out of tiny nozzles, bubbles are produced during ink charging operation under reduced pressure and film bonding operation, which in turn causes inconvenience that the ink spouts out of the ink cartridge.
By the way, an ink cartridge used for serial type ink jet printers requires that an ink supply needle projecting from the back of a recording head be correctly aligned with an ink supply port independently of its load ability to a carriage.
To achieve such object, a loading mechanism for loading an ink cartridge to a carriage proposed in Japanese Utility Model Publication No. Hei 7-32049 is characterized as pushing an engaging projection toward the recording head while engaging the engaging projection with an engaging groove formed in a side surface of the ink cartridge by turning a lever, the engaging projection projecting from an inner side surface of the lever.
However, such loading mechanism suffers from the disadvantage that since the engaging projection turns about the pivot together with the lever, a component force directed at right angles to the recording head is applied to the ink cartridge due to friction with the engaging projection. As a result, such component force is likely to break the supply needle projecting from the back of the recording head.